CentOS 6.5 vs. CentOS 7.0 NAS Performance Comparison

After years of development, RedHat finally released the next major version of RedHat Enterprise Linux (RHEL) v7. The new major version of RedHat Enterprise Linux
provides a large number of new features and improvements including:

Linux Kernel v3.10

XFS as the default file system

LVM-snapshots for XFS and EXT4

Support for Linux Containers

RedHat Enterprise Linux is an enterprise-grade Linux distribution, which is frequently used in corporate data centers as an operating system for NAS storage devices.
From the performance point of view, the new Linux kernel and the new default file system may have a significant impact on a NAS storage device and therefore it is
very important to understand how the newly released RedHat Enterprise Linux version 7.0 compares to the last stable version 6.5.

In order to test the performance of NAS capabilities in the new version of RedHat Enterprise Linux, we have used 2 identical virtual machines running CentOS 6.5
(64-Bit) and CentOS 7.0 (64-Bit) with each one configured to use 4 CPU cores, 4 GB of system memory and installed on the same 8-core physical server with 32 GB
of system memory running the Windows Server 2008 R2 (64-Bit) host operating system.

Host Server Configuration:

Intel Xeon E5-2667 v2 8-core CPU

32 GB of System Memory

Gigabit Ethernet Network

Crucial M550 256 GB System Disk

Crucial M550 512 GB Data Disk For Virtual Machines

Windows Server 2008 R2 (64-Bit) Host Operating System

VirtualBox v4.2.24 (64-Bit) Virtualization Solution

Guest Virtual Machines Configuration:

4 CPU Cores

4 GB of System Memory

Gigabit Ethernet Network

20 GB System Disk Located on Crucial M550 256 GB SSD

256 GB Data Disk Located on Crucial M550 512 GB SSD

An identical set of tests with an identical set of files has been performed on both operating systems and before each test the virtual machine has been restarted.
All tests were performed using DiskBoss v4.7.28, which is capable of analyzing disk space usage, classifying files, searching
duplicate files, synchronizing files, copying files and deleting files using a number of parallel threads. Each operating system has been tested using an identical
set of benchmarks including:

Average NAS performance results from both operating systems were normalized and compared relative to the last stable version of CentOS 6.5. According to the normalized
NAS performance results, which show a normalized average NAS performance for all types of benchmarks for the newly released CentOS 7.0 compared to the last stable
version of CentOS 6.5, the new version of the operating system is slower in random write operations and file delete operations, but faster in all types of file
read operations, disk space analysis operations and duplicate files search operations.

For users required to write a large number of small files to a NAS storage device, the newly released RedHat Enterprise Linux v7.0 is 22% slower compared
to the last stable RedHat Enterprise Linux version 6.5.

For users required to read a large number of small files from a NAS storage device, the newly released RedHat Enterprise Linux v7.0 is 2.9% faster compared
to the last stable RedHat Enterprise Linux version 6.5.

For users required to write medium-sized files to a NAS storage device, the newly released RedHat Enterprise Linux v7.0 is 12.6% slower compared
to the last stable RedHat Enterprise Linux version 6.5.

When reading medium-sized files from a NAS storage device, the newly released RedHat Enterprise Linux v7.0 is up to 17.2% faster compared
to the last stable RedHat Enterprise Linux version 6.5.

When writing a small number of large files to a NAS storage device, the newly released RedHat Enterprise Linux v7.0 is up to 5.4% faster compared
to the last stable RedHat Enterprise Linux version 6.5.

When reading a small number of large files from a NAS storage device, the newly released RedHat Enterprise Linux v7.0 is up to 21.7% faster compared
to the last stable RedHat Enterprise Linux version 6.5.

For disk space analysis and file classification operations, which mostly require to read directory structures from a NAS storage device,
the newly released RedHat Enterprise Linux v7.0 is up to 4.2% faster compared to the last stable RedHat Enterprise Linux version 6.5.

For duplicate files search operations, which require a large number of random read operations, the newly released RedHat Enterprise Linux v7.0 is up to 7.6% faster compared
to the last stable RedHat Enterprise Linux version 6.5.

For file delete operations, the newly released RedHat Enterprise Linux v7.0 is 11.9% slower compared to the last stable RedHat Enterprise Linux version 6.5.

Conclusions:

RedHat Enterprise Linux v7.0 - the newly released version of RedHat Enterprise Linux significantly improves the performance of all types of file read operations, disk space analysis operations and duplicate files search operations. On the other hand, random file write operations, especially for large numbers of small files, and file delete operations are slower than in the last stable version of RedHat Enterprise Linux 6.5.

RedHat Enterprise Linux v6.5 - the last stable version of RedHat Enterprise Linux 6.5 still delivers superior performance for random file write operations and file delete operations, but for users requiring faster file read and/or file analysis operations it is highly recommended to upgrade to the newly released RedHat Enterprise Linux version 7.

* This performance review has been prepared for information purposes only and we strongly advise
you to make your own performance evaluations using your specific hardware components and datasets.